This application claims the priority benefit of Taiwan application serial no. 90122432, filed Sep. 11, 2001.
1. Field of the Invention
The present invention relates to a monolithic microwave integrated circuit (MMIC) package. More specifically, the present invention relates to a flip chip type MMIC package.
2. Description of the Related Art
Currently, the operational frequency of a common micro/millimeter wave integrated circuit is from about 3-30 GHz to 30-300 GHz. The functions and applications of the microwave/millimeter wave integrated circuit are limited to the package thereof. Therefore, to succeed in the MMIC market, a MMIC package having a high operational frequency, low parasitic capacitance and parasitic conductance, superior heat dissipation performance, compact body, low production cost, and an ability to mass production is required.
FIG. 1 is a schematic cross-sectional view of a conventional MMIC package. The package shown in FIG. 1 is a small outline integrated circuit (SOIC) package that is most widely used. The chip 104 is attached to a die region 106 of a leadframe 102 by surface mounting. A bonding wire 108 is used to electrically connect the chip 104 to the leadframe 102. A sealing material 110 covers and fixes the wire 108, the chip 104 and, a portion of the leadframe 106. A package is formed after molding with a capsulatant 112, which protects the electric properties from being deteriorated by moisture, dusts, or the like in the atmosphere. However, the leadframe may generate serious parasitic capacitance and parasitic conductance effects.
An approach to solve the above problem has been proposed. As shown in FIG. 2, a schematic cross-sectional view of another conventional MMIC package with an insulation substrate used as a carrier for a MMIC die 204 of a MMIC package 200. The insulation substrate has an upper surface and a lower surface. The upper surface and the lower surface are provided with a plurality of contacts 202a and 202b, respectively. The contact 202a and the contact 202b are electrically connected through a via hole 202c. After the MMIC die 204 is attached to the insulation substrate 202, a bonding wire 206 is used to electrically connect the contact 203 on the MMIC die 204 to the contact 202a on the insulation substrate. Finally, the sealing material 208 covers and fixes the MMIC die 204 and the bonding wire 206. A package is formed after molding with a capsulatant 210.
In the prior, the bonding wire may result in parasitic capacitance and parasitic conductance effects, which causes impedance and self-oscillation.
It is one object of the present invention to provide a MMIC package, which reduces the parasitic capacitance and the parasitic conductance.
It is another object of the present invention to provide a MMIC package, which has a heat sink bonded to an active region of the MMIC die to effectively dissipate heat.
It is still another object of the present invention to provide a MMIC package in which the electric connection between the chip and the insulation substrate is achieved by the flip chip technology instead of the wire bonding technology, resulting in a reduced package size.
It is still another object of the present invention to provide a MMIC package, which is applicable to the surface mount technology and is able to put into mass production.
In order to accomplish the above and other objects of the present invention, a monolithic microwave integrated circuit (MMIC) package comprising a MMIC die, a heat sink, an insulation substrate, and a sealing material is provided. The MMIC die has an active region and a peripheral region. The heat sink is located in the active region of the MMIC die. A plurality of bonding pads are located in the peripheral region. The insulation substrate has an opening and a plurality of transit ports. The opening is used to contain the heat sink, and the transit ports are electrically connected to the bonding pads. The sealing material is filled between the insulation substrate and the MMIC die to cover the whole MMIC die so that the MMIC die is fixed to the insulation substrate and is protected.
The transit ports of the insulation substrate are electrically connected to the bonding pads on the MMIC die by bumps. These bumps can be formed on the bonding pads of the MMIC die or on the transit port of the insulation substrate.
The heat sink that is used for the present invention is slightly smaller than the opening.
In one aspect of the present invention, the transit port of the insulation substrate further comprises a first contact, a second contact, and a via hole. The first contact is located on the upper surface of the insulation substrate. The second contact is located on he lower surface of the insulation substrate. The via hole is located in the insulation substrate and is used to electrically connect the first contact to the second contact.
In another aspect of the present invention, the transit port of the insulation substrate comprises a first contact and a second contact, which are not electrically connected to each other through a via hole. The first and second contacts disconnected to each other are used as dummy contacts.
The first contact on the upper surface of the insulation substrate is electrically connected to the bonding pad of the MMIC die.
The heat sink is bonded to the active region of the MMIC die by an adhesive layer. The adhesive layer can be made of a low dielectric material or a thermally conductive compound.